1. Field of the Invention
The present invention relates to a syringe. More particularly the syringe includes a safety sheath selectively movable by one hand to positions whereby the needle may be exposed or covered, one of the needle covering positions being automatically locked when the sheath is moved thereto.
2. Background of the Prior Art
Protection for medical personnel from inadvertent contact with contaminated syringe needles has become an increasing concern particularly because of the severity of certain infectious diseases which have developed. For example, the AIDS virus has been shown to be spread to persons who come into contact with a contaminated needle after the needle was used for a patient carrying the virus.
Numerous attempts have been made to protect medical personnel, patients and anyone in the area when syringes are used by providing various shielding devices for the needles. For example, U.S. Pat. No. 4,969,877 relates to a syringe which includes an outer casing into which the needle may be retracted after use. U.S. Pat. No. 4,973,316 relates to a one handed retractable sheath safety syringe. A number of other attempts at providing protection for safety syringe needles have been made.
None of the safety devices developed to date provide relatively simple and quick one hand application whereby the user may simply slide a protective device into several positions with one position being a locked position which is irreversible by normal action of the user. Further, there remains a need for such safety syringes which would be usable as an injecting syringe or as an aspirating syringe, all with one hand operation, while being simply automatically convertible to a configuration whereby the needle is covered and protected while preventing inadvertent re-exposure of the needle. The present invention provides such a safety syringe.